[Madwifi] Madwifi SIOCGIWSCAN buffer overflow // France Telecom

["Tyop?" <tyoptyop () gmail com>]

Name:           Madwifi SIOCGIWSCAN buffer overflow
Vendor:         http://www.madwifi.org
Release date:   December, 7th 2006
CVE ID:         CVE-2006-6332
Authors:        Laurent BUTTI, Jerome RAZNIEWSKI, Julien TINNES


1. Description

There  is a  buffer  overflow  in the  madwifi  Atheros  driver in  some
functions called by SIOCSIWSCAN ioctl.

This  issue is  remotely exploitable  because ioctl  SIOCSIWSCAN may  be
called  automatically by  some connexion  managers (either  directly, by
using iwlib or  by calling iwlist) when  trying to get a  list of nearby
access points.

2. Details

There  is  a  stack  buffer   overflow  in  both  the  giwscan_cb()  and
encode_ie()  functions  (ieee80211_wireless.c).   The  first  issue,  in
giwscan_cb, is  related with insufficient  checks on the length  in some
802.11 information elements which are controlled by the attacker:

       memcpy(buf, se->se_wpa_ie, se->se_wpa_ie[1] + 2);

The second issue is improper  boundary checks in encode_ie() where ielen
is never checked with bufsize.

       for (i = 0; i < ielen && bufsize > 2; i++)
               p += sprintf(p, "%02x", ie[i]);

A properly  crafted 802.11 beacon  or probe response frame  will trigger
the bug  when a process tries  to get scanning results  by calling ioctl
SIOCGIWSCAN. The information element used  by the attacker can be either
WPA  IE, RSN  IE, WMM  IE or  ATH IE  and will  lead to  a kernel  stack
overflow.

3. Vendor status

The vendor was notified on December, 6th 2006 and issued version 0.9.2.1
to correct the issue.

4. Authors

Laurent BUTTI <laurent.butti at francetelecom.com>
Jerome RAZNIEWSKI <jerome.razniewski at francetelecom.com>
Julien TINNES <julien.tinnes at francetelecom.com>


-- 
Tyop?

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